the arctic tundra case study
- Created by: beaw18
- Created on: 21-05-19 09:14
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- arctic tundra
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- area of 8 million km
- found in northern canada, alaska, siberia
- conditions get more severe with latitude
- for 8-9 months of year tundra has temps below freezing
- ground is permanently frozen, top meter thaws in summer
- soil underlain by permafrost
- water cycle
- low annual precipitation of 50-350 mm. most of this is snow
- small moisture store in atmosphere - low temps and absolute humidity
- limited transpiration - sparse vegetation and small growing season
- evaporation rates low due to lack of sun energy, energy generally used to melt snow
- groundwater and soil water stores small as permafrost is a barrier to infiltration, percolation and groundwater flow
- increased river flow in spring as snow and ice thaw
- extensive ponds, wetlands and lakes during summer as drainage is poor
- physical factors, seasonal changes and stores and flows of water
- average temps well below freezing, most water is stored in ice, snow and permafrost
- summer - active (top meter) thaws and liquid water pools on surface
- drainage is poor as water cannot infiltrate frozen soils
- sub zero temps prevent evapotranspiration
- permeability low as rock basin is crystalline
- carbon cycle
- permafrost a carbon sink - 1600 gt of carbon
- accumulation of carbon is slow due to low temps which slow decomposition rates
- amount of carbon in soils is 5x than above ground biomass
- plants grow rapidly in short summer - long days of sunlight allow max growing
- npp is less than 200 grams per square meter a year
- biomass small - between 4 and 29 tonnes a year
- tundra plants input carbon rich litter into soil. microorganism activity increase releasing co2 through respiration
- pockets of unfrozen soil act as co2 and methane sources
- debatable if this will happen, scientists investigating
- physical factors, seasonal changes and stores and flows of carbon
- carbon mostly stored in decomposing plants trapped in permafrost for last 50,000 years
- low temps and water logging slow decomposition and respiration rates - flow to atmosphere slow
- oil and gas production impacts
- the north slope of alaska - oil and gas discovered at prudhoe bay in 1968
- despite extremities, pipelines, roads, completed in 70/80s
- 90s - bay accounted for 3/4 of US's domestic oil production
- today only 6% due to growth is US shale gas, and production costs
- damages permafrost from construction and operations
- snow darkened by dirt, absorbs heat
- vegetation which insulated vegetation gone
- heat from settlements diffused directly
- melting permafrost releases co2 and methane - green house gases
- Untitled
- the north slope of alaska - oil and gas discovered at prudhoe bay in 1968
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